This invention relates to a riser reactor system for producing ethylene and propylene from a hydrocarbon feed stream. The invention further relates to a device including multiple feed streams for enhancing ethylene and propylene production.
Ethylene and propylene are light olefin hydrocarbons and are important chemicals for use in the production of other useful materials, such as polyethylene and polypropylene. Other materials that are important and produced from ethylene and propylene include vinyl chloride, ethylene oxide, ethylbenzene, and alcohol. Essentially all of ethylene and propylene is produced by steam cracking of pyrolysis of hydrocarbons. Hydrocarbons used as feedstock for light olefin production include natural gas, petroleum liquids, and carbonaceous materials including coal, recycled plastic or any organic material.
The amounts of ethylene and propylene produced are often limited by the process and the percentage of the ethylene and propylene produced is often fairly low. Factors affecting the conversion include residence time, temperature of the operation and composition of the feedstock. As the economy grows and expands, the demand for light olefins will increase. Because of the limited availability in the production of light olefins from current methods, new methods are desired for increasing yields from existing sources of hydrocarbons. In addition, new inventions to reactor designs can enhance light olefin production.
The invention relates to a riser reactor system for the conversion of a hydrocarbon feedstock to ethylene and propylene. The riser reactor system includes at least one riser reactor unit with a plurality of inlet ports, a catalyst outlet port, and a gas outlet port. The gas-catalyst separation unit with an inlet port is in fluid communication with at least one riser reactor unit catalyst outlet port, and includes a gas outlet port and a catalyst outlet port. The riser reactor system also includes a catalyst regeneration unit with an inlet port in fluid communication with the catalyst outlet port of the gas-catalyst separation unit, and a catalyst outlet port in fluid communication with at least one of the inlet ports of the riser reactor unit. The invention provides for increased control and increased conversion of a hydrocarbon feedstock to ethylene and propylene.
In one embodiment, the riser reactor system includes a plurality of riser reactor units wherein each riser reactor unit has a catalyst inlet port, a gas inlet port, catalyst outlet ports and a gas outlet port. The system also includes a manifold having an inlet port and a plurality of outlet ports wherein the inlet port is in fluid communication with the catalyst regeneration unit outlet port and each riser reactor catalyst inlet port is in fluid communication with an outlet port of the manifold. The riser reactor system may further include a hydrocarbon separation unit having a gas inlet port in fluid communication with the plurality of riser reactor units gas outlet ports, and wherein a hydrocarbon separation unit separates ethylene and propylene from the hydrocarbon gas.
Optionally, the riser reactor system is a plurality of reactor units and may include the reactor units in a series wherein the gas outlet port from a reactor unit is in fluid communication with the gas inlet port of a successive reactor unit. The riser reactor system may further include at least one heat exchanger disposed between successive reactor units for further controlling the temperature of the gas entering a reactor unit. This provides control to prevent the gas temperature from rising to a level where unfavorable thermal cracking will occur.
Another embodiment of the present invention includes a countercurrent riser reactor system for selectively converting hydrocarbons to ethylene and propylene. The system includes a riser reactor unit with a plurality of inlet ports for admitting gas and catalyst to the unit, and a gas outlet port and a catalyst outlet port. The system further includes a gas-catalyst separation unit with an inlet port in fluid communication with the riser reactor catalyst outlet port. The system further includes a catalyst regeneration unit for regenerating catalyst to be fed to the riser reactor unit wherein the catalyst stream comprises catalyst particles sized to exceed the terminal velocity of the superficial gas velocity of the gas stream. An aspect of the countercurrent riser reactor system optionally may include a plurality of reactor units, and optionally may include heat exchanger units disposed between successive reactor units. This provides for additional control of the temperature of the gas to prevent the gas from reaching temperatures where unfavorable thermal cracking may occur.
Other objects, advantages and applications of the present invention will become apparent after a detailed description of the invention.